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avglvltree: delete: replaced recursion with loop

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git-svn-id: trunk@36144 -
This commit is contained in:
mattias 2012-03-17 22:53:00 +00:00
parent 53591f4e6a
commit 33958d7756
1 changed files with 66 additions and 61 deletions
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127
components/lazutils/avglvltree.pas
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@ -1085,81 +1085,86 @@ var
OldBalance: integer;
Child: TAvgLvlTreeNode;
begin
OldParent:=ANode.Parent;
OldBalance:=ANode.Balance;
ANode.Parent:=nil;
ANode.Balance:=0;
if (ANode.Left<>nil) and (ANode.Right<>nil) then begin
// DelNode has both: Left and Right
// Replace ANode with symmetric Successor
while (ANode.Left<>nil) and (ANode.Right<>nil) do begin
// ANode has both: Left and Right
// Switch ANode position with Successor
// Because ANode.Right<>nil the Successor is a child of ANode
Successor:=ANode.FindSuccessor;
OldBalance:=ANode.Balance;
ANode.Balance:=Successor.Balance;
Successor.Balance:=OldBalance;
OldParent:=ANode.Parent;
OldLeft:=ANode.Left;
OldRight:=ANode.Right;
OldSuccParent:=Successor.Parent;
OldSuccLeft:=Successor.Left;
OldSuccRight:=Successor.Right;
ANode.Balance:=Successor.Balance;
Successor.Balance:=OldBalance;
if (OldSuccParent<>ANode) then begin
// at least one node between ANode and Successor
ANode.Parent:=Successor.Parent;
if (OldSuccParent.Left=Successor) then
OldSuccParent.Left:=ANode
else
OldSuccParent.Right:=ANode;
Successor.Right:=OldRight;
OldRight.Parent:=Successor;
end else begin
// Successor is right child of ANode
ANode.Parent:=Successor;
Successor.Right:=ANode;
end;
Successor.Left:=OldLeft;
if OldLeft<>nil then
OldLeft.Parent:=Successor;
Successor.Parent:=OldParent;
ANode.Left:=OldSuccLeft;
if ANode.Left<>nil then
ANode.Left.Parent:=ANode;
ANode.Right:=OldSuccRight;
if ANode.Right<>nil then
ANode.Right.Parent:=ANode;
if (OldParent<>nil) then begin
if (OldParent.Left=ANode) then
if OldParent<>nil then begin
if OldParent.Left=ANode then
OldParent.Left:=Successor
else
OldParent.Right:=Successor;
end else
fRoot:=Successor;
// delete Node as usual
Delete(ANode);
end else begin
// left or right is nil
if ANode.Left<>nil then
Child:=ANode.Left
else
Child:=ANode.Right;
if Child<>nil then
Child.Parent:=OldParent;
if (OldParent<>nil) then begin
// Node has parent
if (OldParent.Left=ANode) then begin
// Node is left child of OldParent
OldParent.Left:=Child;
Inc(OldParent.Balance);
end else begin
// Node is right child of OldParent
OldParent.Right:=Child;
Dec(OldParent.Balance);
end;
BalanceAfterDelete(OldParent);
Successor.Parent:=OldParent;
if OldSuccParent<>ANode then begin
if OldSuccParent.Left=Successor then
OldSuccParent.Left:=ANode
else
OldSuccParent.Right:=ANode;
Successor.Right:=OldRight;
ANode.Parent:=OldSuccParent;
if OldRight<>nil then
OldRight.Parent:=Successor;
end else begin
// Node is the only node of tree
fRoot:=Child;
{ ANode Successor
\ => \
Successor ANode }
Successor.Right:=ANode;
ANode.Parent:=Successor;
end;
dec(FCount);
ANode.Free;
ANode.Left:=OldSuccLeft;
if OldSuccLeft<>nil then
OldSuccLeft.Parent:=ANode;
ANode.Right:=OldSuccRight;
if OldSuccRight<>nil then
OldSuccRight.Parent:=ANode;
Successor.Left:=OldLeft;
if OldLeft<>nil then
OldLeft.Parent:=Successor;
end;
// left or right is nil
OldParent:=ANode.Parent;
ANode.Parent:=nil;
if ANode.Left<>nil then
Child:=ANode.Left
else
Child:=ANode.Right;
if Child<>nil then
Child.Parent:=OldParent;
if (OldParent<>nil) then begin
// Node has parent
if (OldParent.Left=ANode) then begin
// Node is left child of OldParent
OldParent.Left:=Child;
Inc(OldParent.Balance);
end else begin
// Node is right child of OldParent
OldParent.Right:=Child;
Dec(OldParent.Balance);
end;
BalanceAfterDelete(OldParent);
end else begin
// Node is the only node of tree
fRoot:=Child;
end;
dec(FCount);
ANode.Free;
end;
procedure TAvgLvlTree.Remove(Data: Pointer);